1-(4-(4-(3,4-dichloro-2-fluorophenylamino)-7-methoxyquinazolin-6-yloxy)piperidin-1-yl)prop-2-en-1-one hydrochloride, as represented by formula (IV) below, is known to have anti-proliferative activities such as anti-cancer activities, and it is considered as an important drug that can selectively and effectively inhibit drug resistance which is induced by cancer cell growth and tyrosine kinase mutations. The free base form of the compound of formula (IV), i.e., 1-(4-(4-(3,4-dichloro-2-fluorophenylamino)-7-methoxyquinazolin-6-yloxy)piperidin-1-yl)prop-2-en-1-one, as represented by formula (I) below, is also known as CAS Registry No. 1092364-38-9.

The compound of formula (I) above may be prepared by the method disclosed in KR Patent No. 1013319, and the detailed reaction process is described in Reaction Scheme 1 below. The compound of formula (I) prepared by Reaction Scheme (I) below may be reacted with hydrochloric acid to yield a hydrochloride salt thereof, i.e., the compound of formula (IV):

wherein R is halogen.
According to the preparation method as described in Reaction Scheme 1 above, compound 10 is subjected to a condensation reaction with formamidine hydrochloride at a high temperature, e.g., 210° C., to yield compound 9, which is then allowed to react with L-methionine in an organic acid such as methylsulfonic acid, whereby the methyl group at the C-6 position of compound 9 is removed to obtain compound 8.
Subsequently, compound 8 is subjected to a protection reaction in anhydrous acetic acid and a base such as pyridine to produce compound 7, which is then subjected to a reaction with inorganic acids such as thionyl chloride, phosphorus oxychloride and the like in the presence of a catalytic amount of N,N-dimethylformamide under a reflux condition to obtain compound 6 in a hydrochloride form.
Compound 6 thus obtained is subjected to a deprotection reaction by stirring in an alcohol solution containing ammonia (e.g., 7N ammonia methanol solution) to produce compound 5. Compound 5 is subjected to a Mitsunobu reaction with tert-butyl 4-hydroxypiperidine-1-carboxylate compound to yield compound 4, which is then subjected to a substitution reaction with aniline in an organic solvent such as 2-propanol or acetonitrile to obtain compound 3. Compound 3 is subjected to a reaction with an organic acid such as trifluoroacetic acid or an inorganic acid such as strong hydrochloric acid in an organic solvent such as dichloromethane, whereby the t-butoxycarbonyl group is deprotected to obtain compound 2. In the Mitsunobu reaction above, diisopropyl azodicarboxylate, diethyl azodicarboxylate or di-t-butyl azodicarboxylate, and triphenylphosphine may be used.
Compound 1, i.e., the compound of formula (I) of the present invention, is prepared by subjecting compound 2 thus obtained to an acylation reaction with acryloyl chloride in a mixture of water and an organic solvent such as tetrahydrofuran and the like, or in dichloromethane in the presence of an inorganic base such as sodium bicarbonate or an organic base such as pyridine or triethylamine. Alternatively, compound 2 is subjected to a condensation reaction with acrylic acid by using a coupling agent, e.g., 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) or 2-(1H-7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate methanaminium (HATU).
In accordance with the above-described method, however, the step for preparing compound 9 may be hazardous because this step is conducted at a high temperature without a solvent, and the reaction may not proceed uniformly. Also, an excessive amount of thionyl chloride is used in the step for preparing compound 5, rendering the subsequent steps difficult. Therefore, this method is not suitable for commercialization.
The most notable drawback to this method for preparing compound 1 is that the yield of the acrylization reaction is very low, e.g., 13%, and also the reaction is accompanied by a number of side reactions, and thus, it requires a purification process by using column chromatography. Also, in the case where compound 3 is prepared by the Mitsunobu reaction, various by-products may be formed, which necessitate a purification step by using column chromatography that requires expensive silica gel and an excessive amount of mobile phase solvents. Therefore, this method is not feasible for commercialization.
Accordingly, the present inventors have endeavored to develop a novel method for preparing the compound of formula (I) in high purity and high yield, which is economical and feasible for commercialization as well.